OpenSUSEs immutable distros are not more reliable than Tumbleweed to my knowledge. There is no reset, rebase, transparency over applied modifications (rpm-ostree status) or other crucial things.
Yes, I think it's basically the same. With Aeon you get a lot of it automated and already set up, which is good if you want the kind of system that Aeon is. It's opinionated, so if you want to tinker or want something else I think Tumbleweed is better.